Turbidity measurement method and turbidimeter

A turbidity measurement method includes irradiating a first irradiation light L1 having a first spectrum E1, detecting a first measured light ML1 based on the first irradiation light L1, irradiating a second irradiation light L2 having a second spectrum E2 different from the first spectrum E1, detecting a second measured light ML2 based on the second irradiation light L2, calculating turbidity of a liquid to be measured, and correcting at least one of a first parameter related to turbidity calculation associated with the first irradiation light L1 and a second parameter related to turbidity calculation associated with the second irradiation light L2 so that the calculated turbidity of the liquid to be measured corresponds to the turbidity of the liquid to be measured as measured using another light source serving as a standard of comparison.